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.\" Copyright (c) 2017, Joyent, Inc.
.\" Copyright 2022 Oxide Computer Company
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.Dd July 2, 2022
.Dt MC_UNICST 9E
.Os
.Sh NAME
.Nm mc_unicst
.Nd set device unicast address
.Sh SYNOPSIS
.In sys/mac_provider.h
.Ft int
.Fo prefix_m_unicst
.Fa "void *driver"
.Fa "const uint8_t *mac"
.Fc
.Sh INTERFACE LEVEL
illumos DDI specific
.Sh PARAMETERS
.Bl -tag -width Fa
.It Fa driver
A pointer to the driver's private data that was passed in via the
.Fa m_pdata
member of the
.Xr mac_register 9S
structure to the
.Xr mac_register 9F
function.
.It Fa mac
A pointer to an array of bytes that contains the new unicast address of
the device.
It is guaranteed to be at least a number of bytes long equal to the length of
the MAC plugin's address length.
For Ethernet devices that length is six bytes,
.Dv ETHERADDRL .
.El
.Sh DESCRIPTION
The
.Fn mc_unicst
entry point is used by the MAC framework to indicate that the device driver
should update the primary MAC address of the device.
In the basic mode of operation, this entry point is required and the device has
a single primary MAC address.
If multiple MAC addresses are required, the device will be placed into
promiscuous mode.
This call should overwrite the existing MAC address that is programmed into the
device.
.Pp
Device drivers that implement the
.Dv MAC_CAPAB_RINGS
capability
.Em must not
implement this interface.
.Pp
As noted in the
.Sy PARAMETERS
section, the
.Fa mac
array is guaranteed to be at least as many bytes as is required to
specify an address; however, it should be assumed to be no longer than
that value.
.Pp
The device driver can optionally assert that the address is in the
valid form for a unicast address and then program the device.
The device driver can access its device soft state by casting the
.Fa device
pointer to the appropriate structure.
As this may be called while other operations are ongoing, the device driver
should employ the appropriate locking while updating the data.
.Pp
It is recommended that device drivers always maintain a copy of the
current unicast address in its soft state so that way it can recover
from various device reset and errors or handle requests to suspend and
resume the device that may result in device registers being cleared.
.Pp
Some devices support multiple MAC address filters.
The
.Fn mc_unicst
entry point only supports a single MAC address.
In this case, devices should only use a single MAC address and replace that MAC
address.
To enable the operating system to take advantage of multiple unicast MAC
address filters, the driver should implement the
.Dv MAC_CAPAB_RINGS
capability.
See
.Xr mac_capab_rings 9E
for more information.
.Sh RETURN VALUES
Upon successful completion, the device driver should have updated its
unicast filter and return
.Sy 0 .
Otherwise, the MAC address should remain unchanged and the driver should
return an appropriate error number.
.Sh ERRORS
The device driver may return one of the following errors.
While this list is not intended to be exhaustive, it is recommended to use one
of these if possible.
.Bl -tag -width Er
.It Er EINVAL
The address
.Fa mac
is not a valid unicast address.
.It Er EIO
The driver encountered a device or transport error while trying to
update the device's state.
.El
.Sh SEE ALSO
.Xr mac 9E ,
.Xr mac_capab_rings 9E ,
.Xr mac_register 9F ,
.Xr mac_register 9S
